Comparison of skin hydration evaluation sites and correlations among skin hydration, transepidermal water loss, SCORAD index, Nottingham eczema severity score, and quality of life in patients with atopic dermatitis

Background: Atopic dermatitis (AD) is characterized by dryness of the skin, pruritus and involvement of the skin flexures. Skin hydration (SH) and integrity, as measured by transepidermal water loss (TEWL), are important parameters for objectively quantifying AD research. Objectives: To evaluate if sites in the forearm are equivalent to the antecubital fossa for standard SH and TEWL measurements; and to determine the correlations among these measurements and scores of disease severity and quality of life. Methods: We evaluated SH and TEWL under standardized conditions at three common measurement sites in the forearm (antecubital flexure, 2 cm below the antecubital flexure, mid-forearm), and determined the SCORing Atopic Dermatitis (SCORAD) score, Nottingham Eczema Severity Score (NESS), and Children's Dermatology Life Quality Index (CDLQI). Results: Significant correlations between clinical scores, SH, and TEWL were obtained at a site 2 cm below the antecubital fossa (r = -0.553, p < 0.001 for SH and SCORAD; r = 0.596, p < 0.001 for TEWL and SCORAD). SH and TEWL were also correlated with long-term severity of AD as measured by NESS (r = -0.494, p = 0.001 for SH; r = 0.430, p = 0.004 for TEWL), while TEWL was significantly correlated with CDLQI (r = 0.323, p = 0.035). Overall, similar significant correlations were obtained at the mid-forearm, but less so at the antecubital fossa. Conclusion: In AD research, three sites on the forearm appear to be convenient for determination of SH and TEWL. This is the first report to demonstrate that significant correlations are obtained among acute and chronic scores of AD disease severity, quality of life, and the bioengineering parameters.